1. Field
This disclosure relates generally to a wireless communication system and, more specifically, to techniques for reducing communication errors in a wireless communication system.
2. Related Art
Wireless networks that employ third-generation partnership project-long term evolution (3GPP-LTE) compliant architectures are currently required to utilize aperiodic channel quality information (CQI) uplink grants when a scheduler (associated with a serving base station (BS)) desires to schedule a downlink data transmission to a user end (UE) or subscriber station (SS). The scheduler utilizes CQI reported by the SS (in response to an aperiodic CQI uplink grant) to determine which portion of a system bandwidth to utilize for a downlink transmission to the SS. With reference to FIG. 1, a table 100 depicts an example physical downlink control channel (PDCCH) format that may be utilized to signal an uplink grant or a downlink assignment to an SS (from a scheduler via a serving BS) via a PDCCH. As is illustrated, the PDCCH format includes: a one-bit format field; a one-bit hopping flag field; a thirteen-bit resource block (RB) assignment field; a five-bit modulation and coding scheme (MCS) field; a two-bit retransmission sequence number (RSN) field; a two-bit transmit power control (TPC) field; a three-bit cyclic shift for a demodulation reference signal (DMRS) field; a one-bit CQI request field; and a sixteen-bit radio network temporary identifier/cyclic redundancy check (RNTI/CRC) field.
A value of the one-bit format field specifies whether a transmission on the PDCCH is an uplink grant or a downlink assignment. A value of the one-bit hopping flag field specifies whether frequency hopping is turned on or off and a value of the thirteen-bit RB assignment field specifies which RBs are assigned to an SS for uplink or downlink transmissions. A value of the five-bit MCS field specifies what MCS is assigned to a transmission. A value of the two-bit RSN field specifies a retransmission sequence and a value of the two-bit TPC field specifies a transmit power level on a physical uplink shared channel (PUSCH). A value of the three-bit cyclic shift for DMRS field specifies a cyclic shift for a DMRS and a value of the one-bit CQI request field specifies whether CQI is requested. Finally, a value of the sixteen-bit RNTI/CRC field specifies a unique identifier for the SS. A scheduler asserts a value in the one-bit CQI request field to request CQI from an SS. As previously noted, a scheduler uses a reported CQI to schedule a downlink transmission for an SS.